The leader of a porters’ union backed by the Congress was arrested in Burrabazar’s Posta on Sunday night on the charge of stealing Rs 5 lakh from a trader.

“Ramji Mishra has been arrested following a complaint by Asit Chatterjee, whose money was stolen. We are also looking for Mishra’s son Dinesh,” said joint commissioner of police, headquarters, Jawed Shamim.

Police said Chatterjee had gone to the office of Calcutta Posta Shramik Sangathan on Strand Bank Road in Posta on Friday with a bag containing around Rs 7.5 lakh to settle a labour problem he had been facing in his business. “He paid Rs 2.5 lakh to Mishra apparently to resolve the dispute and kept the bag on the table,” said an officer of North Port police station.

Chatterjee said in his complaint that he was talking to Dinesh and Kameshwar Singh, another leader of the union, after the payment. “I saw Dinesh leeve the office and seconds later realised that my bag was missing. I raised a hue and cry. Mishra told me that he would ensure that I got back my money within two days,” the trader mentioned in the FIR.

Chatterjee alleged that Mishra later washed his hands of the matter. “There were three persons — Mishra, Dinesh and Singh — in the office when the bag containing the money disappeared. After a preliminary probe, we suspect the trio had a link with the theft,” said an officer of North Port police station.

Police sources said Mishra was a secretary of the Posta unit of the porters’ union, affiliated to the Congress-backed Intuc. When asked about the incident, Pradip Bhattacharya, the president of the Intuc state unit, said: “I haven’t heard about the arrest but if there is a complaint, the law will take its course.”

The cops said that Posta traders had hurled charges of extortion against Mishra. “There are allegations that Mishra used to extort money from traders, threatening that porters would not work for them if they did not pay up,” said an officer.